1. Field of the Invention
The present invention relates to a method and/or a system and/or a device and/or a terminal equipment usable for a mechanism for managing/controlling at least one connection between two or more parties via a communication network. In particular, the present invention relates a method and/or a system and/or a device and/or a terminal equipment usable for a mechanism for managing/controlling at a connection in a case where an established connection is to be terminated.
2. Related Prior Art
In the last years, an increasingly extension of communication networks, e.g. of wire based communication networks, such as the Integrated Services Digital Network (ISDN), or wireless communication networks, such as the cdma2000 (code division multiple access) system, cellular 3rd generation communication networks like the Universal Mobile Telecommunications System (UMTS), the General Packet Radio System (GPRS), or other wireless communication system, such as the Wireless Local Area Network (WLAN), took place all over the world. Various organizations, such as the 3rd Generation Partnership Project (3GPP), the International Telecommunication Union (ITU), 3rd Generation Partnership Project 2 (3GPP2), Internet Engineering Task Force (IETF), and the like are working on standards for telecommunication network and multiple access environments.
In general, the system structure of a communication network is such that one party, e.g. a subscriber's user equipment, such as a mobile station, a mobile phone, a fixed phone, a personal computer (PC), a laptop, a personal digital assistant (PDA) or the like, is connected via transceivers and interfaces, such as an air interface, a wired interface or the like, to an access network subsystem. The access network subsystem controls the communication connection to and from the user equipment and is connected via an interface to a corresponding core or backbone network subsystem. The core (or backbone) network subsystem switches the data transmitted via the communication connection to a destination party, such as another user equipment, a service provider (server/proxy), or another communication network. It is to be noted that the core network subsystem may be connected to a plurality of access network subsystems. Depending on the used communication network, the actual network structure may vary, as known for those skilled in the art and defined in respective specifications, for example, for UMTS, GSM and the like.
Generally, for properly establishing and handling a communication connection between network elements such as the user equipment and another user terminal, a database, a server, etc., one or more intermediate network elements such as control network elements, support nodes or service nodes are involved. One or more connection parameters are used for defining connection characteristics. This includes, for example, a packet based data transmission protocol information, such as a PDP (Packet Data Protocol) context information, information about quality of service (QoS) requested or provided, charging-related information, such as a charging class, etc.
On the other hand, regarding the end of a connection, an established communication connection may be terminated by different reasons. For example, one of the parties may end the connection. However, it may also be the case that the communication connection is terminated due to network related reasons. This includes, for example, a deterioration of the connection quality resulting in a loss of bearer for one terminal equipment of the participating parties, or the like.
In case of a network related reason for terminating a connection, there are proposed several methods in different communication network types how this connection termination is to be handled.
As a first example, a conventional method for terminating a connection in a 3GPP Internet Protocol (IP) Multimedia System (IMS) Release 6 environment is described.
In general, IMS enables the provision of multimedia services. IP multimedia services are based on an IETF defined session control capability which, along with multimedia bearers, utilizes an IP-Connectivity Access Network. The IMS, in particular the Core Network (CN) subsystem thereof, enables the convergence of, and access to, voice, video, messaging, data and web-based technologies for the wireless user. An overview of IMS is provided, for example, in 3GPP TS 23.228 V.6.4.1 (2004-01).
The IMS utilizes different types of network elements which include, amongst others: a Policy Decision Function (PDF) acting as a policy decision element for service based local policy control, which makes policy decisions on the basis of session and media related information; one or more Application Functions (AF) being elements offering applications that require the control of IP bearer resources, such as UMTS PS resources, GPRS domain resources; a Proxy Call Session Control Function (P-CSCF) element as a session management element which represents one example for an AF, and which is acting a proxy, i.e. it accepts requests and services them internally or forwards the; a Gateway GPRS Support Node (GGSN) for sending requests and receiving decisions from the PDF. The network elements are connected by specified interfaces, such as a Go interface between the GGSN and the PDF, a Gq interface between the PDF and the P-CSCF (in case of 3GPP IMS rel. 6, for example), and the like. It is to be noted that, as known by those skilled in the art, also other network elements and interfaces are used within the IMS system, like other CSCFs, such as a Serving-CSCF, an Interrogating-CSCF, and the like. However, as such elements are not of significant importance for the present invention, a detailed description thereof is omitted herein.
In order to achieve access independence and to maintain a smooth interoperation with wireline terminals across the Internet, the IMS attempts to be conformant to IETF “Internet standards”. Therefore, the interfaces specified conform as far as possible to IETF “Internet standards” for the cases where an IETF protocol has been selected, e.g. Session Initiated Protocol (SIP). SIP is an application-layer control protocol for establishing, modifying and terminating multimedia sessions, such as Internet telephony calls, and is defined, for example, in IETF RFC (Request for Comments) 3261 (June 2002).
Regarding the termination of a connection or session of a party/user in an 3GPP IMS rel. 6 environment, as described for example in 3GPP specification TS 24.229 V.6.1.0 (December 2003), the P-CSCF has to release all dialogs associated with the served user, when it receives an indication that the radio interface resources are no longer available for a served user (e.g. in case of a loss of bearer). The indication is received on the Gq interface from the PDF according to the procedures described in 3GPP specification TS 29.209 V.1.0.0 (May 2004). The Gq interface is used for service based policy set-up information exchange between the PDF and the AF. At the Gq interface, Diameter base protocol as defined in IETF RFC 3588 (September 2003) is used. The Diameter base protocol provides an Authentication, Authorization and Accounting (AAA) framework for applications such as network access or IP mobility. According to TS 29.209, when the GGSN informs the PDF of the PDP context release (via Go interface by using Common Open Policy Service protocol (COPS) signalling, defined below), the PDF informs the AF (like the P-CSCF) about this event by sending an Abort-Session-Request (ASR) message with the appropriate Session-Abort-Cause Attribute Value Pair (AVP) value. The ASR command, indicated by a Command-Code field set to a value of 274, for example, and a so-called “R” bit set in the Command Flags field, is sent by the PDF to inform the AF that bearer resources for the authorized session are not available (anymore).
It is to be noted that a similar mechanism is also defined for a 3GPP2 MultiMedia Domain (MMD) environment, and a description of the implementation of an IP multimedia call control protocol used in such a 3GPP2 MMD environment is provided in the 3GPP2 specification X.S0013.4. In 3GPP2 MMD networks the gateway node is a Packet Data Serving Node (PDSN) instead of a GGSN according to 3GPP IMS.
Next, another example for a conventional method for terminating a connection in a 3GPP IMS Release 5 environment is described.
In 3GPP Release 5, different to the IMS 3GPP rel. 6 system, the PDF may be part of the P-CSCF. In this case, the GGSN is connected to the P-CSCF/PDF entity via the Go interface. The policy control mechanism in the 3GPP IMS rel. 5 environment is described, for example, in the 3GPP specification TS 29.207 V.5.6.0 (December 2003).
Similar to the mechanism described in connection with the 3GPP IMS rel. 6, the P-CSCF has to release all dialogs associated with the served user when it receives an indication that the radio interface resources are no longer available for a served user (e.g. in case of a loss of bearer). According to TS 29.207, the indication is received via the Go interface from the PDF. The GGSN informs the PDF of the bearer release related to the SIP session of the served party by sending a Common Open Policy Service protocol (COPS) Delete Request State (DRQ) message. COPS is a protocol developed for use between a policy server and a network element, and is described, for example, in IETF RFC 2748 (January 2000).
In both the 3GPP IMS rel. 6 and rel. 5 environments, in reaction to the receipt of the indication, the P-CSCF performs a dialog release procedure. Releasing dialogs means for the P-CSCF to generate a (SIP) BYE request based on the information saved for the related dialog/connection during dialog/connection establishment between the parties which is transmitted to the served party by means of a SIP signalling.
However, when the party, i.e. the user equipment, receives the BYE request generated by the P-CSCF, the user using the UE to receive does not get any indication about the reason caused to send the BYE request, i.e. why exactly the connection is terminated. This may lead to an impression of the user that the BYE request is sent by the other party's terminal. In other words, a user is not in the position to recognize why the call was released. He can easily assume that the called party hung up although the reason was actually in bad quality of radio interface (loss of bearer). A “called party” can also be any service in the network which an end user is using. In this case a user could hold the view that the problem was in the service even though the reason for the release was in bearer.